When we have to study a particular faculty of the human mind in its sources, its content, and its limits; then from the nature of human knowledge we must begin with its parts, with an accurate and complete exposition of them; complete, namely, so far as is possible in the present state of our knowledge of its elements.But there is another thing to be attended to which is of a more philosophical and architectonic character, namely, to grasp correctly the idea of the whole, and from thence to get a view of all those parts as mutually related by the aid of pure reason, and by means of their derivation from the concept of the whole.This is only possible through the most intimate acquaintance with the system; and those who find the first inquiry too troublesome, and do not think it worth their while to attain such an acquaintance, cannot reach the second stage, namely, the general view, which is a synthetical return to that which had previously been given analytically.It is no wonder then if they find inconsistencies everywhere, although the gaps which these indicate are not in the system itself, but in their own incoherent train of thought.
I have no fear, as regards this treatise, of the reproach that Iwish to introduce a new language, since the sort of knowledge here in question has itself somewhat of an everyday character.Nor even in the case of the former critique could this reproach occur to anyone who had thought it through and not merely turned over the leaves.To invent new words where the language has no lack of expressions for given notions is a childish effort to distinguish oneself from the crowd, if not by new and true thoughts, yet by new patches on the old garment.If, therefore, the readers of that work know any more familiar expressions which are as suitable to the thought as those seem to me to be, or if they think they can show the futility of these thoughts themselves and hence that of the expression, they would, in the first case, very much oblige me, for I only desire to be understood: and, in the second case, they would deserve well of philosophy.But, as long as these thoughts stand, I very much doubt that suitable and yet more common expressions for them can be found.**I am more afraid in the present treatise of occasional misconception in respect of some expressions which I have chosen with the greatest care in order that the notion to which they point may not be missed.Thus, in the table of categories of the Practical reason under the title of Modality, the Permitted, and forbidden (in a practical objective point of view, possible and impossible) have almost the same meaning in common language as the next category, duty and contrary to duty.Here, however, the former means what coincides with, or contradicts, a merely possible practical precept (for example, the solution of all problems of geometry and mechanics);the latter, what is similarly related to a law actually present in the reason; and this distinction is not quite foreign even to common language, although somewhat unusual.For example, it is forbidden to an orator, as such, to forge new words or constructions; in a certain degree this is permitted to a poet; in neither case is there any question of duty.For if anyone chooses to forfeit his reputation as an orator, no one can prevent him.We have here only to do with the distinction of imperatives into problematical, assertorial, and apodeictic.Similarly in the note in which I have pared the moral ideas of practical perfection in different philosophical schools, I have distinguished the idea of wisdom from that of holiness, although I have stated that essentially and objectively they are the same.But in that place I understand by the former only that wisdom to which man (the Stoic) lays claim; therefore I take it subjectively as an attribute alleged to belong to man.
(Perhaps the expression virtue, with which also the made great show, would better mark the characteristic of his school.) The expression of a postulate of pure practical reason might give most occasion to misapprehension in case the reader confounded it with the signification of the postulates in pure mathematics, which carry apodeictic certainty with them.These, however, postulate the possibility of an action, the object of which has been previously recognized a priori in theory as possible, and that with perfect certainty.But the former postulates the possibility of an object itself (God and the immortality of the soul) from apodeictic practical laws, and therefore only for the purposes of a practical reason.
This certainty of the postulated possibility then is not at all theoretic, and consequently not apodeictic; that is to say, it is not a known necessity as regards the object, but a necessary supposition as regards the subject, necessary for the obedience to its objective but practical laws.It is, therefore, merely a necessary hypothesis.I could find no better expression for this rational necessity, which is subjective, but yet true and unconditional.
In this manner, then, the a priori principles of two faculties of the mind, the faculty of cognition and that of desire, would be found and determined as to the conditions, extent, and limits of their use, and thus a sure foundation be paid for a scientific system of philosophy, both theoretic and practical.
Nothing worse could happen to these labours than that anyone should make the unexpected discovery that there neither is, nor can be, any a priori knowledge at all.But there is no danger of this.